1. Field of the Invention
This invention relates to an apparatus for vapor phase processing such as soldering, fusing or brazing.
An article on which the vapor phase processing is to be performed is heated to a preselected temperature appropriate for the vapor phase processing by condensing hot saturated vapor of liquid on the article. Although the present invention is not to be construed as limited to soldering, it is most readily understood in the context of soldering.
2. Description of the Prior Art
U.S. Pat. No. 3,904,102 discloses a vapor phase processing apparatus of the type wherein an article is heated to a preselected temperature for vapor phase processing comprising: a vessel containing a liquid having a boiling point at least equal to the preselected temperature, into and out of which the article is transported; heating means for boiling the liquid to produce vapor; and cooling means for condensing the vapor. In this apparatus, the heating means is provided inside the vessel. Although an external source of heat such as a hot plate may be applied to the vessel as a supplemental heating means, the main heating means remains inside the vessel. This apparatus has several disadvantages.
Since the heating means inside the vessel must be submerged in the liquid to prevent overheating, a quantity of liquid is always needed in the vessel so that the liquid level is maintained above the heating means.
Conventionally, flux is used with elements to be soldered in the soldering operation, and the flux merged in the liquid is deposited on the external surface of the heating means to degrade the thermal conductivity of the heating means.
Moreover, the existence of the heating means inside the vessel prevents easy cleaning of the interior of the vessel.
The other prior art listed below also has the above disadvantages:
U.S. Pat. No. 3,866,307;
U.S. Pat. No. 4,389,797;
U.S. Pat. No. Re. 30,399.